Detector for alarm systems



F. E. CRAWFORD. DETECTOR FOR ALARM SYSTEMS. APPLICATION FILED, AUG-12, 19H].

Patented July 25, 1922.

Ms W w r v 1... f v 3 2 J .w r W h N 1 Ed f i; W W & @QMW Y ma FRANKLIN E. CRAWFORD, F VIINCHESTER, MASSACHUSETTS, ASSIGNOR T0 BANK- ERE- ELEC'JJRIC. PROTECTIVE ASSOCIATION; OF BOSTON, MASSACHUSETTS, A' COR,-

PORATION OF MASSACHUSETTS;

htdftlhht ii l tihl DETECTOR FOR ALARM. SYSTEMS.

raeaeoi;

Application filed August 12, 1918. Serial No; 249,375,

T 0 all whom it may concern: Be 1t known that I, FRANKLIN E. GRA\V- FORD, a citizen of the United States, and

resident of Winchester, in the county of Middlesex and State of Massachusetts, have. invented new and useful Improvements in Detectors for Alarm Systems, of which the following is a specification.

This invention relates to burglar alarm systems of the kind which have a closed main or controlling circuit, in which the lnterruptlon or variatlon of the current will" cause the alarm to sound. The system relates to the general class illustrated in Letters Patent of the'United States to Coleman No.v 627,054, dated June 13, 1899, to which reference may be had for the details of an appropriate alarm mechanism time controlled mechanism for operating switches,

indicators,and other details. l y

In systems of this. kind the current in the main circuit which controls the alarm, is divided at the vault or other guarded structure, into two paths, one of which passes" through what may be termed the door circuit, controlled by the opening and closing of'the door, and the other of which passes through what may be termed a supplementary circuit, which excludes or passes around the door without passing through the door circuit. This permits the current to be left on the main or controlling circuit through the supplementary circuit, so that the alarm will not operate while the doors are open during business hours; but upon the closing of the doors, and consequently of the door circuit, when the guarded structure is to be closed up and left, the supplementary circuit is left open, so thatthe interruption of the door circuit, by any tam pering with the door, will cause the alarm to be given.

The present invention contemplatesthe combination with a burglar alarm system of 5 this type, of a detectormechanlsm, pref-- erably contained in a second guarded struc ture distant fromthe first guarded struc ture and under 'the control of a'diiferent person, which will-automatically correct any failureon th'e part of the operator at the first 'station'properly to adjust the system to" leave forthe-night, and-so cause the alarm' to 'be given if the door of the guarded structureis not properly closed or is wrongfully casing or housing containing the alarm mechanism. The housing 2 is preferably electrically protected in the manner explained in said Patent No. 627,054, or in any well'known or'suitable manner, so that access cannot be had to the interior without causing an alarm to be given. This housing may. be located within or adjacent to the guarded structure itself, or at a'police station, or other point remote from the guarded structure;

The main or controlling circuit 4 includes the door circuit P. which is controlled by the opening and closing of the door 3 of the guarded structure, and the supplementary circuit 4 ,.which passes around or excludes. the door, and which is preferably a shunt circuit, as shown. in the-drawings. 5 represents a second'guarded structure, which may he a-protectedcabinet' located at a distance from the first guarded structure and intended to be under the control of Within the alarm housing 2 is a balanced relay orgalvanometer 7, or some other electrical device which will respond to variations or interruptions 0t the current passing through the controlling circuit 4:. Such appliance may be termed, generally, a re sponsive' device, and the alarm mechanism is controlled by the respon sive device. The alarm circuit 8" is 1 a local circuitand has its ownindependent battery 9, within the housing 2. The circuit 8 includes an electro magnet 10, the needle or other moving part of the responsive device 7, and the contacts at either side of said needle. The alarm device, which may be of any desired form.

the needle of the responsive device will be held between its contacts thereby maintain ing an open circuit through GlQCtlOlHElgllGt 10 and preventing the alarm from sounding.

- Should the circuit 1 be interrupted by the opening of either door 3 or 6 (disregarding for the moment the supplementary circuit 3 which excludes the doors) the responsive device 7 would instantly close the alarm circuit 8 and cause the alarm to operate.

In order that the current maybe kept on the main or controlling circuit, or part of it, and therefore keep the responsive device normal, and prevent the sounding of the alarm when the doors of the guarded structure 1 are open for business, I employ the supplementary or shunt circuit 49, which provides a path through which the current of the main circuit may pass without passing through the doors or through the circuit controlled by. the doors. The supplementary circuit 1- includes a switch 15,. which is preferably located within the guarded structure 1. The switch 15 is preferably controlled in part by an automatic time-{piece 16, which may be set so as to close the circuit let only at the beginning of business hours when the door 3 is opened, and in part by manually operable means which preferably extends outside the guarded structure; Themanually operable means illustrated in the drawings comprises a magnet-20: in circuit with a battery 21 and button switch and may be suitably concealed.

; At theend of business hours, when the atcircuit 4 would be interrupted and the alarm i tendant closes the door 3, it is his duty manually to open switch 15, so that if the door circuit should be broken, either vthroughaccidentor design, the current in control given. The supplementary circuit may also include an electrically controlled indicator. 14c, of any approved type, to indicate the condition of the circuits.

When the system thus far described is operated, disregarding for the present the second guarded structure 5, the time-piece 16 acts automatically before'business hours to close switch 15 and therefore to close the circuit around the door. 3. The person in charge may then open door 3, thereby opening thedoor-circuit, without operating the alarm, since the coils of relay 7 will be still energized. The switch 15 will remain closed until manually opened, so that during the hours while the vault is being used the door 3 may be either open or closed Without affecting the alarm. After business hours the attendant closes and secures the door 3 of the guarded structure 1, and then manually opens switch 15 in the supplementary circuit. If under these conditions the door circuit should be interrupted the alarmwould be given.

In case the attendant should fail, through neglect or intention, to open switch 15 upon adjusting the system to leave for the night, the door 8 might be opened and the door circuit broken, without giving the alarm. It theprincipal object of the present invention to provide against this situation.

To this end I provide the detector station, which should be under the control of an ofiicial of the vault concern, or some trusted:

person other than the operator at the first .plementary circuit, and so render thealarm subjectto interruptions of the door circuit, whether or not the attendant properly performs his duty by opening switch 15 at the first guarded structure. Said detector sta:

tion is preferably protected by a second guarded structure 5, in the form of a eabinet, having a door 6, the opening and closing of which opens and closes the door cir cuit. Within the second guarded structure 5 is a switch 17 adapted to open and close the supplementary circuit 4: at the detector station. This switch 17 is automatically controlled by a time-piece which may be set so as tokeep the switch closed during business 1 hours while the vault is being used, and open at night or out of business hours.

Thus, if the switch 15, in guarded structure a switch 22. The switch 22 may be a push 1, is not properly opened When the door 3 is closed for the night, the automatic time con trol 18, set to operate a predetermined time, will correct the omission and open the supplementary circuit at, and place the system in condition to give the alarm in case the door 3 is tampered with, notwithstanding the switch 15 has not been-properlyoperof usual construction controlled by th cur rent in supplementary circuit P, to indicate the condition of the circuits.

I claim: v

1. In an electrical burglar alarm system, a guarded structure, an alarm station, an electrical circuit for controlling actuation of the alarm at said station, said circuit comprising two paths at the guarded structure, one a door circuit controlled by the door and the other a supplementary circuit excluding the door, means to control the supplementary circuit at said guarded structure, a detector station distant from said guarded structure, said supplementary circuit passing through said detector station, and mechanism at said station for controlling the supplementary circuit independently of said controlling means at said guarded structure, and a second guarded structure containing the control mechanism at the detector station.

2. In an electric burglar alarm system, a guarded structure, an alarm station, it normally closed electrical circuit for controlling actuation of said alarm upon substantial cessation of current flow through said circuit, said circuit comprising two paths at the guarded station, one a door circuit controlled by the door and the other a supplementary circuit excluding the door, manually operated means for closing said supplementary circuit at said guarded structure, a detector station distant from said guarded structure, said supplementary circuit passing through said detector station and automatic time controlled means at said detector station to control the supplementary circuit independently of said controlling means at said guarded structure.

3. In an electric burglar alarm system, a guarded structure, an alarm station having an alarm device therein, means for controlling the actuation of said alarm device comprising an electrical circuit having two paths at the guarded station, one a door circuit controlled by the door and the other a supplementary circuit excluding the door, manually operated means for closing said supplementary circuit at said guarded structure, automatic time controlled means for opening said supplementary circuit at said guarded structure, a detector station distant from said guarded structure, said supplementary circuit comprising a loop passing through said detector station; and automatic time controlled means at said station to control the supplementary circuit independently of said controlling means at said guarded structure.

4. In an electric burglar alarm system, a guarded structure, an alarm station having an alarm device therein, means for controlling the actuation of said alarm device comprising an electrical circuit having two paths at the guarded station, one a door circuit controlled by the door and the other a supplementary circuit excluding the door, manually operated means for closing said supplementary circuit at said guarded structure, a detector station distant "from said guarded structure, said circuit passing through said detector station and automatic time controlled means at said station to control the supplementary circuit independently of said controlling means at said guarded structure, and a second guarded structure containing the control mechanism at the detector station and having a door adapted to open and close said door circuit at the detector station.

5. An electric burglar alarm system comprising a guarded structure having a door, an alarm device distant therefrom, a detector station remote from said guarded structure and alarm device, an electrical circuit for controlling said alarm device, said circuit having two paths, one of said paths extending through both the guarded structure and the detector station, and the other of said paths being controlled by the door of the guarded structure, and independent means at the guarded structure and the detector station respectively for determining current flow in the first of said paths.

Signed by me at Boston, Massachusetts, this second day of August, 1918.

FRANKLIN E. CRAIVFORD. 

